H1N1 Vaccine and Miscarriages
But back to the main story – Adams and other anti-vaccine cranks have been claiming that the H1N1 vaccine is associated with an increased risk of miscarriage (loss of a child prior to 20 weeks) and still birth (loss after 20 weeks) – collectively called spontaneous abortions. This claim is not based upon any scientific data, however.
Adams based the Natural News article (actually written by staff writer Ethan Huff) on this report by the National Coalition of Organized Women (NCOW). This article is also not a scientific report, but a press release. What were their methods?
NCOW collected the data from pregnant women (age 17-45 years) that occurred after they were administered a 2009 A-H1N1 flu vaccine. The raw data is available on the website.
Using the Vaccine Adverse Event Reporting System (VAERS), including updates through July 11, 2010 as a second ascertainment source, capture-recapture statistical methods* were used to estimate the true number of miscarriages and stillbirths following A-H1N1 flu vaccination in the U.S. Typically, even so-called “complete” studies conducted by the CDC have been shown to miss from 10% to 90% of the actual cases because of under-reporting.
Hmmm…so they combined reports from VAERS and from their own data collection. There is no indication that they controlled in any way for double counting – women who reported their miscarriage to both VAERS and NCOW.
I was also interested in their statistical methods for estimating the “true” rate of miscarriages from these reports. They indicate that cases may be underreported by “10-90%” – that’s quite a range. So someone did a fancy statistical manipulation to “estimate” the true rate based upon these two sources of reporting.
That someone is Paul G King – a notorious (in my opinion) anti-vaccine crank, who also is the NCOW science adviser. I have score of e-mail from King who likes to SPAM scientists and skeptics with crank nit-picky deconstructions of scientific or “pro-vaccine” articles. King is hardcore anti-vaccine, and is hardly an objective scientist.
His analysis amounts to a pile of assumptions used to inflate the number of apparent cases of miscarriages in women receiving the H1N1 vaccine.
I wanted to review the “raw data” that was promised in the press release, but all I could find on their website was this list of 72 anecdotal reports.
From the anecdotal reports in VAERS (219 total reports) and solicited by NCOW, how can King or anyone else conclude that any of these cases were caused by the H1N1 vaccine? In order to do that you would have to demonstrate that the number of cases exceed the background rate – an analysis which is conspicuously absent.
Fortunately, actually scientists, who understand the need to compare incidence to the background, did an analysis prior to the use of the H1N1 vaccine. Here is the entire abstract:
Because of the advent of a new influenza A H1N1 strain, many countries have begun mass immunisation programmes. Awareness of the background rates of possible adverse events will be a crucial part of assessment of possible vaccine safety concerns and will help to separate legitimate safety concerns from events that are temporally associated with but not caused by vaccination. We identified background rates of selected medical events for several countries. Rates of disease events varied by age, sex, method of ascertainment, and geography. Highly visible health conditions, such as Guillain-Barré syndrome, spontaneous abortion, or even death, will occur in coincident temporal association with novel influenza vaccination. On the basis of the reviewed data, if a cohort of 10 million individuals was vaccinated in the UK, 21.5 cases of Guillain-Barré syndrome and 5.75 cases of sudden death would be expected to occur within 6 weeks of vaccination as coincident background cases. In female vaccinees in the USA, 86.3 cases of optic neuritis per 10 million population would be expected within 6 weeks of vaccination. 397 per 1 million vaccinated pregnant women would be predicted to have a spontaneous abortion within 1 day of vaccination.
Spontaneous miscarriages are common – so common that for every 1 million vaccinated pregnant women, there would be 397 cases of miscarriage within 24 hours of receiving the vaccine, by chance alone, without any effect from the vaccine itself. (There are > 4 million births per year in the US and about 50% of pregnant women received the H1N1 vaccine last season.) This is greater than the number of cases reported through VAERS and the NCOW. But the NCOW, in their press release, assumes that all reported cases were caused by the vaccine, when there is no reason to believe that any of them were.